Investigators looking into the fatal crash of a Learjet in Florida have said they found pieces of the horizontal tail section more than a mile from where the aircraft made impact, killing all nine aboard and leaving a fiery crater in the ground.

National Transportation Safety Board (NTSB) member Tom Chapman said during a news conference on Tuesday that the discovery of tail parts broken into three pieces confirms the plane was breaking apart before it hit the ground.

The official said the plane wouldn’t have been able to pull up from its nose dive without the tail intact, and he was not sure it would have been effective even if it was complete because of the aircraft’s extreme rate of descent.

The jet was flying from Austin, Texas, to the Bahamas on Sunday when it appears to have flown into a thunderstorm at 35,000ft, causing – according to radio transmissions from co-pilot Nathalia Filgueiras – icing on the jet and turbulence, causing it to climb and fall by more than 700ft before it began to dive.

In harrowing communications, Filgueiras, 20, told air traffic controllers that the plane was descending at 8,000ft per minute, then 10,000ft per minute. During one of her final transmissions she said: “Declare an emergency 722 Bravo Delta, we are in an overspeed condition descending 20,000ft per minute.”

Seconds later, it crashed in to the ground near a trailer park and exploded into a fireball at the intersection of Military Trail and Cresthaven Boulevard in Palm Beach.

The victims of the crash have been identified by relatives as technology entrepreneur Adam Robinson; his wife, Helen Sharp; and their two young children. Family friends Rachael Reed and Charmi Fehr also died in the crash, as did the family’s nanny, Anita Maria Cetina.

The pilot of the plane has been identified as 55-year-old Jeff Gregory by his employer, East Coast Jets, a charter aviation company based in Allentown, Pennsylvania. “Our prayers go out to Jeff’s family, his fellow crew member, the passengers and everyone affected by this heart breaking tragedy,” the company said in a statement.

In the NTSB briefing on Tuesday, Chapman encouraged anyone living in the area to leave any pieces that may look as if they belong to the aircraft alone and to contact the NTSB or local authorities.

He said the NTSB would work to lay out the recovered pieces of the plane in a way that “remakes” the aircraft in order to determine what may have occurred.

Filgueiras reportedly texted her boyfriend before the situation turned critical: “I’ve got turbulence, I’ve got ice.”

Chapman said on Monday that weather would be a key focus of the investigation. A preliminary report describing what happened will be released in about a month, but it will likely take more than a year to determine the exact cause of the crash.